Dead load (kentledge) A structure over the test pile. Ground anchorage either by tension piles or ground anchors. Bi-directional (Osterberg-cell)

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1 Introduction Fugro LOADTEST Overview STATIC LOAD TESTING O-cell Bi-directional testing State of the art Dr Melvin England Fugro LOADTEST Static load tests Previous/existing technology Developments O-cell static loading tests Conclusions Date 27 th January 21 Fugro LOADTEST Reaction systems for static load tests: LOADTEST Inc started in 1991 Operating around the world from 5 LOADTEST offices 45 staff mostly engineers Some of our staff are recognised leading experts in various forms of pile testing 1 M turnover (1/2 USA) Portable test systems allow easy access to very remote locations LOADTEST acquired Fugro as new owners in Jan 29 and LOADTEST can now operate from any of the Fugro offices around the world and call on the resources of Fugro where necessary. Dead load (kentledge) A structure over the test pile Ground anchorage either by tension piles or ground anchors. Bi-directional (Osterberg-cell) Oil-rig module used as Kentledge Test on group of 9 precast piles to 2MN 1

2 Ready assembled reaction systems Reaction systems 2MN 4 MN Bi-directional testing ABU-DHABI 5.5 MN 1 MN GREAT MOSQUE ABU-DHABI SHEIKH ZAYED BRIDGE ABU-DHABI Zone of influence Zone of influence Reaction beam on anchor piles Kentledge Zone of influence Zone of influence Kentledge on piles Bi-directional test 2

3 Safety considerations Kentledge collapse Due to platform/ground failure From FPS Load testing handbook 26 Reaction Beam collapse COMPLETELY AUTOMATED Due to tension bar failure From FPS Load testing handbook 26 BI-DIRECTIONAL O-CELL O LOAD TESTS How it works Introduction To Osterberg Cell technology Advantages & Limitations Examples Current usage and costs 3

4 Bi-directional schematic Bi-directional schematic Comparison of O-cell and Traditional Tests O-cell Static Load Test Advantages Very high loading capability Gets load into rock sockets (or other zone of interest) Cost, safety and space advantages No additional reaction system needed Doubles effective jack load Can measure directly skin friction and end bearing Post-test grouting techniques allow for testing of production piles O-Cell Instrumentation Single O-cell Bearing Plate Assembly Top and Bottom Plates are Welded to the O-cell O-cell / Plate System is Welded into the Rebar Cage 4

5 O-cell Test Components O-cell TM fitted with bearing plates attached to cage Multi-cell assembly - attaching O-cells O to bottom plate Cone-shaped tremie guide Multi-cell assembly - attaching top plate Lifting the Cage and Attached O-cell Assembly Other O-cell Assemblies Once the Cage With Attached O-cell is Carefully Lifted, it is Installed into the Shaft Excavation O-cells can be Placed at two Levels in the Shaft to Isolate Distinct Shaft Elements The O-cell Need Not be Attached to a Rebar Cage 5

6 Multilevel testing Multilevel testing Stage 1 Middle cell closed Test is performed in stages Lower cell pressurised Multilevel testing Stage 1 Multilevel testing Stage 2 Downward movement below bottom O-Cell (MN) Middle cell pressurised Lower cell draining -6-7 Multilevel testing Stage 2 Multilevel testing Stage 3 Downward movement below middle O-Cell (MN) Middle cell pressurised Lower cell hydraulically closed -45 6

7 Multilevel testing Stage 3 Multilevel testing Stage Downward movement below middle O-Cell (MN) End of Stage 2 testing, Bottom O-cell hydraulic lines closed - allowing load transfer to end bearing (MN) Upward movement above middle O-Cell Equivalent top load-settlement curve Test Setups Settlement (mm) Load (MN) World record 16 MN Advantage Space Requirements O-cell Test Limitations Preselected shaft 2 ton Conventional 3 ton Conventional Maximum load limited by weaker of end bearing or skin friction Test results need interpretation Top of the pile is not tested structurally tested 2 ton O-cell Test 3 ton O-cell Test Top load movement curve must be calculated From the sum of measured behaviour; From the sum of modeled behaviour; Finite element; 7

8 Equivalent TLT Assumptions Analysis of O-cell test results Rigid shaft (includes OLT elastic compression) L-Movement compatibility, friction and end bearing Corrections for direction of skin friction Factor = 1 clays, rock sockets Correction for direction of loading can be used Factor =.8 Equivalent tension test Correction for additional TLT elastic compression- conservative, iterations not needed Good practical agreements Sum of measured results Measured behaviour Sum of components Measured plus additional elastic shortening Comparison test curves Kentledge Test versus O-cell equivalent top load-settlement curve Settlement (mm) Kentledge Test O-cell Test Top Load (MN) 8

9 Advantage High Loads Incheon 2 nd Link, Korea World Record History Location Diameter Depth Maximum Load Ohio River Bridge, Kentucky ( 1992 ) 1.8m ( 6 ft. ) 36m ( 117 ft. ) 54 MN ( 6,2 tons ) St. Mary s River, Georgia (1996 ) 1.5m ( 5 ft. ) 23m ( 75 ft. ) 65 MN ( 7,3 tons ) Penang, Malaysia ( 1996 ) 6x1m barrette 91m ( 3 ft. ) 97 MN ( 11, tons ) Apalachicola River, Florida ( 1997 ) 2.75m ( 9 ft. ) 39m ( 127 ft. ) 133 MN ( 15, tons ) Tucson, Arizona ( 21 ) 2.4m ( 7.9 ft. ) 41m ( 135 ft. ) 151 MN ( 17, tons ) Pomeroy - Mason WV, Ohio River 2.4m (8 ft.) 26m (86ft.) 163 MN (18,4 tons) Incheon 2 nd Crossing Korea 2.4m 3.m (8 ft. 1ft.) 67m (22ft.) 279 MN (31,35 tons) Incheon 2nd Link, Korea Incheon 2nd Link, Korea Osterberg Cell Load-Movement Curves Advantage Rock Sockets 6 5 T L T O L T 4 P 3 Displacement ( mm ) 2 1 Upward Top of O-cell Overburden -1 Downward Base of O-cell -2 Rock Q O-cell Gross Load ( MN ) Ub & Eb difficult to interpret Uncertain Distribution Little or No Top Load Gets into base May Need Model Shaft Less Distribution Uncertainty All Load into Socket Can Test Full Scale 9

10 Applications O-cells in CFA piles Bored piles (wet and dry) CFA piles Driven Piles Cast in-situ (with and without permanent steel casing) Precast Steel tubular piles Barrettes O-cells in CFA piles O-cells in CFA piles Maximum size/loads tested to date Pile Diameter [mm] Pile Length [m] O-cell Diameter [mm] x54 Mobilised Load [MN] O-cells in PRECAST piles Barrettes Sizes tested to date Pile Section 3 mm 45 mm 6mm 75 mm 1

11 St. Petersburg, Russia St. Petersburg, Russia 3 MN Reaction system 6 m deep 9 MN capacity 9 MN O-cell test Kiev Ukraine: 9 MN Barrette Maximum size/loads tested to date 7.m x 1.2 m 5 m deep loaded to 11 MN T shaped: Multiple tremie pipes 2.8 x 4. m loaded to 7MN Maximum size/loads tested to date Applications: Bridges Cooper river Jiangsu Sutong UAE: Multilevel; 8 m deep; 22 MN mobilised Confederation Panama 2 nd Bridge 11

12 Applications: Buildings Osterberg Cells Installed 35 3 Actual Projected Venetian Hotel, Las Vegas, NV Four Seasons Hotel Miami, FL One Raffles Quay, Singapore O-cell Tests World-wide COMPARISON OF LOAD TESTING COSTS CONVENTIONAL VS. O-CELL Conventional O-cell COST/ MN Key >3 Upcoming/In progress TEST LOAD - MN Bi-directional testing Advantages No external reaction system No anchor piles Little or no heavy transport requirements Only half the stresses applied to the concrete For large tests a significant cost saving Disadvantages Pile test not exactly as a full load test. Maximum load applied limited Jack is expendable and needs fitting during pile installation Conclusions Bi-directional testing routinely reveals more about the geotechnical behaviour than a traditional top-down loading test. (Over 14 tests worldwide). O-cell testing much safer than traditional top-loading As the test loads increase the more cost effective and attractive O-cell testing becomes. 12

13 Providing confidence in foundations through load testing - around the world. Thank You A member of the Fugro Group of companies Florida, USA UAE LONDON SINGAPORE KOREA Date 27 th January 21 13